Extended waveform capture
The Waveform Recorder module’s Pre-trigger Records setup register specifies how many pre-event records are saved with each triggered recording. The Post-trigger Records setup register specifies how many post-event records are saved with each triggered recording.
Both Pre-trigger Records and Post-trigger Records are set to zero by default. To configure the waveform recorder for extended waveform capture, either or both of these setup registers must be set to a non-zero positive integer value. If you do this, you must also set the Record Delay Cycles setup register to zero in order to properly configure the extended waveform capture.
One waveform record is defined by the Waveform Recorder module’s Format setup register, expressed as (number of samples per cycle) x (number of cycles per waveform record). For example, if Format is set to 512x4, that means one waveform record is made up of 4 cycles of waveform data at 512 samples per cycle resolution.
|A||Waveform recording triggered|
|B||Waveform record captured at trigger|
|C||Pre-trigger waveform records captured|
|D||Post-trigger waveform records captured|
The waveform log set for each triggered recording is equal to the sum of Pre-trigger Records + Post-trigger Records + 1 (where 1 is the actual record when the Waveform Recorder module’s Record input was triggered).
For example, if Pre-trigger Records is set to 2 and Post-trigger Records is set to 6, the number of records for each waveform log set is 9:
The waveform log set for the extended waveform capture = [pre-trigger records] + [actual trigger record] + [post-trigger records]. The total waveform records captured in this example is 2 + 1 + 6 = 9.
When extended waveform capture is enabled, both Buffer Depth and Depth setup registers must be set to a positive integer multiple of the waveform log set.